Image Credit: Fountain Mountain | Griswold Pump Company
Fountain pumps are designed to supply the flow of water to fountains and devices used for aesthetic purposes and aeration in residential, commercial, and industrial applications. Fountain pumps may be configured for use indoors or outdoors and are typically differentiated by the size of the pool or pond and whether the application is decorative or functional. Some fountain pumps are even solar powered and can work in conjunction with a well pump to create special garden or landscape features such as waterfalls.
Image Credit: PondUSA
Fountain pumps can be classified into types based on a number of factors: operating method, application, and whether the pump is external or submersible.
All pumps are designed to operate on either a dynamic or positive displacement principle. Dynamic pumps, and their subtype centrifugal pumps, utilize fluid momentum and velocity to generate pump pressure while positive displacement pumps use expanding and contracting cavities to move fluids. Dynamic pumps produce a variable flow suited for generating high flow rates with low viscosity fluids, while positive displacement pumps produce a constant flow suited for producing high pressures (and low flow rates) with high viscosity fluids.
Fountain pumps are typically centrifugal pumps, which move water using pressure from centrifugal force created by the movement of an impeller. A fountain pump functions like a sump pump, except that the water is fed back into the pond or reservoir rather than out of it. Specifically, the pump moves the water to an aerator or a fountain device that sprays water from the surface. The free flowing water gathers oxygen as it falls back to the surface, providing aeration and enabling microbial action in the breakdown of wastewater or providing oxygenation for fish in ponds or farming tanks.
A fountain pump setup may look something like this, with a filter in place above the pump to prevent clogging. Image Credit: FTS Aquatics
Fountain pumps include two subtypes based on application: commercial and industrial.
Commercial fountain pumps are used mainly for decorative purposes and come in a variety of configurations, including indoor and outdoor pumps. Decorative fountain pumps can also be used in tabletop or garden fountains, where the fountain machinery is contained in an above-ground reservoir or sump rather than a pond or pool.
Indoor pumps are used in small indoor fountains and decorative devices, and typically have low flow rates.
- Outdoor fountain pumps can pump substantially more water per hour than indoor fountain pumps. They are used with outdoor fountain fixtures for aesthetics and with pools and ponds for aeration.
Industrial fountain pumps are used to aerate wastewater produced from manufacturing processes, to treat sewage, or to treat water for municipal use. Fountain pumps are also used to circulate stagnant water to reduce the build up of algae or the population of mosquitoes. They are typically more rugged than consumer versions, designed to provide higher flow rates and pressures for a variety of media.
External vs. Submersible
Fountain pumps can also be either submersible or external.
Submersible pumps have the pump motor hermetically sealed in the pump body, allowing the entire system to be submerged within the water reservoir or water source. These pumps are easier to install than external pumps, and typically are less expensive.
External pumps may require a more involved setup to install, but are generally more efficient. For turning larger ponds and reservoirs, this means noticably lower operating costs. External pumps are almost always better suited to handle the back pressure associated with the use of a pressurized external filter. They are easier to clean and repair, and the also generally last longer.
The primary specifications to consider when selecting fountain pumps are flowrate, pump head, pressure, horsepower, power rating, and outlet diameter.
- Flowrate describes the rate of volume discharge through the pump, usually given in gallons per minute (gpm) or gallons per hour (gph).
- Head defines the energy supplied to liquid (per unit weight) by the pump. It is expressed as a column height of liquid (either vertical lift or suction), given in feet of head (ft).
- Pressure describes the operational pressure of the pump. It is usually given in pounds per square inch (psi) or bar.
- Horsepower indicates the output power of the pump, measured in units of horsepower (hp).
- Power rating indicates the power required to operate the pump, measured in Watts (W) or horsepower (hp). Since many fountain pumps are electric, some manufacturers will instead specify the voltage (in volts or V) or current (in amps or A). The power rating is the product of the voltage and current ratings (power = voltage x current).
- Outlet diameter is the size of the discharge or outlet connection of the pump. Inner diameter (I.D.) describes the size of the inner opening while outer diameter (O.D.) specifies the entire opening size including the pipe or nozzle thickness.
For a more in depth discussion of pump specifications and performance, visit GlobalSpec's Pump Flow page.
Matching Pump Specifications to the Application
Fountain pumps must be sized to fit the needs of the fountain, reservoir, or pond they are servicing. Considerations include:
Turning- To "turn" the water in a reservoir means to cycle all of the water through the pump. Sizing the pump to the desired turning rate is important for providing proper aeration.
Selection Tip:For ponds with a pressurized filter, turn the water every two hours (for a 2000 gallon reservoir, a 1000 gph pump is needed). For most other types of ponds, turn the water every hour (2000 gallon reservoir requires a 2000 gph pump).
Pipe sizing - Pipes and tubes must fit the pump and allow proper flow. Pipe sizes that are too small will restrict flow, while pump sizes which are too large will result in an insufficient outlet velocity.
Total head - Specifying the pump head requires determining the total head (resistance) of the system. This is determined from a combination of factors, including friction and elevation. In the case of the setup pictured below, the total head would include the length of the pipe (friction head) and the difference in height between the two pond surfaces (elevation head).
Image Credit: Pond Pumps